Research And Design Of High Efficiency And High Power Interleaved Parallel Buck Converter

With the increasingly intense exploration of Marine resources in various countries,China has also carried out exploration of deep-sea resources and energy development,including the construction of submarine scientific observation network,which is of great significance to break through the frontier of science and solve the major scientific and technological problems of national security.The long-term submarine scientific observation network is mainly composed of shore-based stations,photoelectric composite cables,connection boxes,scientific observation instruments,etc.The main function of the connection box includes the step-down of shore-based HVDC.Due to the wide range of input voltage,large step-down amplitude and large output power,two-stage step-down is planned to be adopted.This topic explores the realization of the post-stage 480-800VDC closed-loop regulated voltage output of 400VDC,and satisfies the power output of 12k W.DC/DC converter is widely used in communication power supply,new energy power generation,and other areas,to make full use of energy and satisfy a variety of applications,the conversion efficiency,power density and reliability index of switching power supply are raised higher requirements,the synchronous rectification,high-frequency ZVS and interleaved parallel technology can effectively improve the performance of converters.Combined with the above three technologies,this topic chooses the topology of two-phase interleave parallel Buck converter with simple structure,high efficiency and reliability,wide voltage regulating range and easy to control as the research object to carry out the research,so as to meet the requirements of high efficiency,high power density and high reliability.The main research contents are as follows.Firstly analyzes combined with synchronous rectification technology in interleaved parallel Buck converter of various mode of inductor current continuous mode,calculates ripples in the circuit,establishes the state space average model of topology,and give appropriate compensation after set the double closed loop feedback system to enhance the steady and dynamic performance of the converter.Secondly analyzes the ZVS working principle of the interleaved parallel Buck converter,on the basis of principle analysis discusses the master tube achieve ZVS condition,determine the joint effect of inductance value L,the duty cycle D of the switch tube and the switching frequency f_s on the over-negative inductor current and the discharge of the parasitic capacitance so as to realize the ZVS of main control tube.The loss of switching tube,inductance and capacitance in hard switching mode and soft switching mode are calculated and compared,and the efficiency advantage of the converter in soft switching mode is shown.Finally,combined with parameter calculation,the simulation platform of hard switching and soft switching of 12k W interleaved parallel Buck converter is built by MATLAB/Simulink simulation software to verify the above theoretical analysis.A hard switching prototype platform with input of 480V-800V and output of 400V/30A was built to realize two-phase equalization of current under various working conditions,and the dynamic performance under load mutation and steady-state performance after switching were better.At the same time,a prototype platform of soft switching with480V-800V input and 400V/20A output was built,which verified the conditions of realizing ZVS of main control tube,and its feasibility and advantages.